2.3. Case definitions

1. Lost honey bee colony is a honey bee colony that:
a) is reduced to such a small number of bees that it cannot perform the normal
biological activities needed for survival (brood rearing, resource gathering)
or

b) has queen problems,
such as drone laying queens or drone laying
worker bees in absence of a queen, which could not be solved or

c) was missing due to
burglary, or didn’t survive fire, inundation, desert storms or similar causes
unrelated to health problems.

d) no longer has any
living bees present.

2. Weak honey bee colony:
A honey bee colony that is not considered as lost, but in which the number of
bees is less than would be expected from the colony size observed at an earlier
inspection.

3. Colony
Depopulation Syndrome (CDS):

This is observed if a honey bee colony
shows the following conditions within a certain time-frame:

a) reduced to no, or only a few
remaining, living bees in the hive and

b) no, or only a few dead bees in or
in front of the hive or at the apiary while

5. Time frames during which
honey bee colony losses occurred can be distinguished as:

a) Time frames related to
seasonal characteristics: For
example winter: the period between the moment that a beekeeper
finished pre-winter preparations for his/her honey bee colonies and the start
of the new foraging season (usually first of “spring”).

b) Fixed time frames:
For example: observations every half year.

It is difficult to come to conclusions on losses with a fixed timeframe
approach since the outcome depends on beekeeper practices such as merging,
splitting, buying and selling of colonies. Recalling the numbers of colonies
involved in these practices later when a questionnaire is disseminated may
easily lead to errors in the data (Van der Zee et al., 2012). Another problem is that no information is collected
on when these increases/reductions were made within the timeframe, with the
effect that colonies bought at the start of a time frame have the same weight
in the risk estimation as colonies bought later on. Not recognising these
problems may severely bias the outcome.